title: ADAM10 overexpression shifts lympho- and myelopoiesis by dysregulating site 2/site 3 cleavage products of Notch.
abstract: Although the physiological consequences of Notch signaling in hematopoiesis have been extensively studied, the differential effects of individual notch cleavage products remain to be elucidated. Given that ADAM10 is a critical regulator of Notch and that its deletion is embryonically lethal, we generated mice that overexpress ADAM10 (ADAM10 transgenic [A10Tg]) at early stages of lympho- and myeloid development. Transgene expression resulted in abrogated B cell development, delayed T cell development in the thymus, and unexpected systemic expansion of CD11b(+)Gr-1(+) cells, also known as myeloid-derived suppressor cells. Mixed bone marrow reconstitution assays demonstrated that transgene expression altered hematopoiesis via a cell-intrinsic mechanism. Consistent with previously reported observations, we hypothesized that ADAM10 overexpression dysregulated Notch by uncoupling the highly regulated proteolysis of Notch receptors. This was confirmed using an in vitro model of hematopoiesis via culturing A10Tg hematopoietic Lineage(-)Sca-1(+)c-Kit(+) cells with OP-9 stromal cells in the presence or absence of Delta-like 1, a primary ligand for Notch. Blockade of the site 2 (S2) and site 3 (S3) cleavage of the Notch receptor demonstrated differential effects on hematopoiesis. OP9-DL1 cultures containing the ADAM10 inhibitor (S2 cleavage site) enhanced and rescued B cell development from wild-type and A10Tg Lineage(-)Sca-1(+)c-Kit(+) cells, respectively. In contrast, blockade of γ-secretase at the S3 cleavage site induced accumulation of the S2 product and consequently prevented B cell development and resulted in myeloid cell accumulation. Collectively, these findings indicate that the differential cleavage of Notch into S2 and S3 products regulated by ADAM10 is critical to hematopoietic cell-fate determination.
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University, Massey Cancer Center, School of Medicine, Richmond, VA 23298, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Gibb
authors.forename: Sheinei J
authors.initials: SJ
authors.lastname: Saleem
authors.forename: Dae-Joong
authors.initials: DJ
authors.lastname: Kang
authors.forename: Mark A
authors.initials: MA
authors.lastname: Subler
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Conrad
mesh_terms: D051722:ADAM Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D000072197:ADAM10 Protein; D053829:Amyloid Precursor Protein Secretases / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D019070:Cell Lineage / Q000235:genetics / Q000276:immunology; D049109:Cell Proliferation; D002478:Cells, Cultured; D006131:Growth Inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism; D006868:Hydrolysis; D038041:Lymphopoiesis / Q000235:genetics* / Q000276:immunology*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D039902:Multipotent Stem Cells / Q000276:immunology / Q000378:metabolism; D023461:Myeloid Progenitor Cells / Q000276:immunology / Q000378:metabolism; D038042:Myelopoiesis / Q000235:genetics* / Q000276:immunology*; D051880:Receptors, Notch / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology / Q000378:metabolism / Q000473:pathology
chemical_list: D006131:Growth Inhibitors; D008565:Membrane Proteins; D051880:Receptors, Notch; D053829:Amyloid Precursor Protein Secretases; D051722:ADAM Proteins; D000072197:ADAM10 Protein; C491234:Adam10 protein, mouse